The invention relates to a suture anchor system for joining pieces of tissue, in particular, for repairing meniscal tears, comprising at least two arrow-shaped or pin-shaped anchor implants joined to one another by a flexible suture fastened to the anchor implants.
The invention further relates to an instrument for inserting such an anchor implant.
To join pieces of tissue, for example, the parts of a meniscus separated from one another by a tear, it is known to introduce into the pieces of tissue arrow-shaped anchor implants which by means of barbs or a barbed design are secured in the pieces of tissue against removal. These implants can directly join the pieces of tissue to be attached to one another by penetrating both pieces of tissue (WO 85/03857; U.S. Pat. No. 5,843,084) or two such arrow-shaped anchor implants are joined together by a flexible intermediate member so as to thereby bridge the junction (EP 0 589 306 A2; EP 0 664 198 B1).
Moreover, a suture anchor system is described in U.S. Pat. No. 5,702,462, in which dart-type anchor implants each have a suture securely attached thereto, and the sutures of various anchor implants are knotted together after insertion of the anchor implants into the tissue so that the pieces of tissue to be joined together are joined by the suture bridges. However, this procedure is relatively complicated as the suture ends of two respective anchor implants have to be knotted together, and, in addition, the knots form a thickening in the suture which may cause irritation of the tissue.
The object of the invention is to so design a generic suture anchor system that it can be installed in a particularly simple way and that, in particular, the formation of knots can be dispensed with.
This object is accomplished in a suture anchor system of the kind described at the outset, in accordance with the invention, in that at least one of the anchor implants has a continuous longitudinal passageway for receiving a longitudinally displaceable core, in that a suture guide for receiving a suture common to all anchor implants for longitudinal displacement in the suture guide is disposed on this anchor implant, in that a clamping device for securing the suture in the suture guide is associated with the suture guide, and in that the clamping device is inactive so long as the core is located inside the longitudinal passageway and only becomes active when the core is pulled out of the longitudinal passageway.
Thus, in contrast to known anchor implants, in the described suture anchor system at least two anchor implants are joined by a common suture, and on at least one of these anchor implants this suture is initially freely displaceable in a suture guide. Therefore, after insertion of the anchor implants in the tissue, the suture can be tensioned in the desired manner between the two anchor implants, and in this tensioned state the suture can then be secured on the anchor implants by the core being pulled out of the longitudinal passageway. Knot formation is no longer necessary, and yet it is possible to tension the suture joining the inserted anchor implants in the desired manner and to thereby secure the pieces of tissue to be joined in relation to one another.
In a first preferred embodiment provision is made for a first anchor implant to be securely fastened to the suture and for all other anchor implants to have a longitudinal passageway with a removable core and a suture guide with a clamping device. In this way, starting with a first anchor implant with a suture securely fastened thereto, any number of further anchor implants can first be displaceably threaded onto the same suture, but after insertion of the anchor implants, the suture can be tensioned between these anchor implants and secured. The suture anchor system may comprise only two anchor implants or a larger number of anchor implants.
The first anchor implant may also have a continuous longitudinal passageway for facilitating in a manner to be described hereinbelow installation of the anchor implant in the piece of tissue.
In another embodiment provision is made for all anchor implants to have a longitudinal passageway with a removable core and a suture guide with a clamping device, i.e., all anchor implants are initially freely displaceable on the suture and are only secured along the suture by removal of the core.
In particular, in such an embodiment it is of advantage for the one end of the suture to carry a stop element which upon tensioning of the suture bears against a piece of tissue and thereby prevents further drawing of the suture into the piece of tissue.
The core may be a ram-shaped part which is pulled out of the anchor implant to activate the clamping device. It is, however, particularly advantageous for the core to be a guide wire which is pushed through the anchor implant and lodged in the tissue, for it is then possible to advance the anchor implant along this guide wire into the desired position in the tissue. Thus, in this embodiment the guide wire both guides the anchor implant during insertion and activates the clamping device for the suture upon pulling out the guide wire.
The guide wire may also serve to position the pieces of tissue to be joined together relative to one another so that upon introducing the anchor implant, the pieces of tissue are secured in the desired position relative to one another. This can prevent these pieces of tissue from being joined in a crooked or overlapping manner.
It is favorable for the anchor implants to carry barbs or barb-like protrusions on their exterior surface so that anchor implants, once inserted, are secured in their position.
The anchor implant and/or the suture preferably consist of absorbable plastic material so these implants disintegrate in the body after completion of the healing process.
The core can render the clamping device active in different ways. For example, in the pushed-in state the core can displace a clamping element, for example, a flexible clamping tongue, movably disposed on the anchor implant, into a position in which this clamping element is unable to effectively block the suture. Once the core is pulled out of the anchor implant, this clamping element, which may, for example, be a barb, engages the suture and thereby prevents displacement of the suture relative to the anchor implant. These clamping elements may be barbs acting on one side or on both sides, i.e., barbs are provided for both directions of displacement of the suture, so the suture is secured against displacement in both directions after removal of the core.
In a particularly preferred embodiment provision is made for the suture guide to comprise a clamping section extending through the longitudinal passageway and a displacement section disposed adjacent the longitudinal passageway, for the core inserted in the anchor implant to block off the clamping section from the displacement section, and for the clamping device to be disposed in the clamping section, whereas the suture is freely displaceable in the displacement section.
In this construction, the clamping section is released by pulling out the core, the suture can move into the clamping section from the displacement section and is thereby secured against longitudinal displacement in the anchor implant.
The clamping device may have a multiplicity of projections or barbs for engaging the suture when the suture enters the clamping device and thereby securing the suture in the anchor implant.
In a particularly preferred embodiment provision is made for the clamping device to be a slot which tapers towards the bottom thereof, and into which the suture is placed and clamped between the side walls thereof when the suture is displaced towards the bottom of the slot.
It is of advantage for guides for the suture which are bent at an angle towards the bottom of the slot to adjoin the slot on both sides thereof. Once the suture is tensioned in these angled guides, it is automatically pulled into the slot, tensioned against the bottom thereof and thereby clamped in the slot.
These guides adjoining the slot may be in the form of channels open or closed at their sides, which extend at either side of the longitudinal passageway substantially parallel thereto in the anchor implant and at one end open into the bottom of the slot. In this way, both ends of the same suture exit the anchor implant on the same side thereof, and the suture thereby forms inside the anchor implant a U-shaped loop which is guided in the slot.
It is advantageous for the slot to extend diametrically through the anchor implant at least in the area of the clamping section.
The side walls of the slot may converge at an acute angle towards the bottom thereof. It is favorable for the side walls to have a concave curvature in cross section.
In a further preferred embodiment provision is made for the clamping section formed by the slot to continue at its end opposite the bottom thereof into the displacement section arranged outside the longitudinal passageway and likewise forming part of the slot, with the side walls of the slot in the displacement section being spaced at a distance from one another which is greater than the diameter of the suture.
The plane of the slot in the displacement section may be bent at an angle in relation to the plane of the slot in the clamping section, preferably at an angle of between 30xc2x0 and 90xc2x0. It is favorable for the slot to be curved in the area of transition between the clamping section and the displacement section so that after removing the core and upon applying tension, the suture readily slides from the displacement section into the clamping section.
Provision may be made for the slot at the outer end of the displacement section to be open towards the outside at the circumferential surface of the anchor implant. This facilitates insertion of the suture into the anchor implant.
The following description of preferred embodiments of the invention serves in conjunction with the drawings to provide a more detailed explanation.